The present invention relates to a brake pad retention system of a disc brake of a motor vehicle, in particular a commercial vehicle.
Numerous construction variants of such brake pad retention systems of disc brakes are known from the prior art.
The brake pads are generally guided in the pad shaft of a brake carrier and secured against a curved pad retention member on a brake caliper. The pad retention member extends over the brake carrier in the form of a pad retention spring. The pad retention spring presses the brake pad against the brake carrier with a force FF. During a braking operation, the brake pad may move counter to the resilient force of the pad retention spring about a rotation point owing to the torque M transmitted to the brake pad, the rotation point being located in this instance in the region of an upper end of the outlet-side carrier horn of the brake carrier.
Since, as a result of the movement of the brake pad, torque may be transmitted to a thrust piece of the brake caliper and a threaded spindle which is arranged thereon, the rotation of the brake pad may lead to undesirable wear adjustment.
In order to prevent such a rotation movement, a positive-locking securement of the brake pad in a brake pad shaft formed by the carrier horns of the brake carrier and a bridge piece of the brake carrier that connects the carrier horns is also not expedient since production-related tolerances of the brake pads and the brake carrier require a minimum play.
An object of the present invention is to effectively prevent the above-described rotation of the brake pad during a braking operation.
This and other objects are achieved by a brake pad retention system of a disc brake of a motor vehicle. The disc brake includes a brake caliper which straddles a brake disc, a brake carrier which is fixed at a vehicle side and which has inlet-side and outlet-side carrier horns and a bridge portion connecting the carrier horns to each other, and at least one brake pad which is provided with a pad carrier plate and a friction pad secured thereto, and which is guided in a pad shaft formed by the carrier horns and the bridge portion. At least one of the carrier horns of the brake carrier and the support face of the pad carrier plate adjacent thereto are able to be fitted to each other in a positive-locking manner with play. At least one brake pad is retained in the pad shaft in a resiliently loaded state via a pad retention spring which extends transversely relative to the axial direction of the brake disc and which can be radially redirected on the brake pad. The at least one pad retention spring is arranged such that the pad retention spring in the assembled state presses the brake pad away from the bridge portion of the brake carrier in a play-free manner against the carrier horns.
A brake pad retention system which is constructed in this manner is distinguished above all in that the at least one pad retention spring is arranged between a side of the brake pad facing the bridge portion of the brake carrier and the bridge portion of the brake carrier in the pad shaft. The pad retention spring in the assembled state presses the brake pad in front of the bridge portion of the brake carrier away in a play-free manner against the carrier horns.
Owing to the arrangement of the pad retention springs, that they do not press the brake pad in the direction of the bridge portion of the brake carrier, but rather in an opposed radially outward direction. The brake pad is pressed directly into the positive-locking connection between the brake pad and brake carrier horn with the force FF, whereby in the force-free state, that is to say, in a state in which no braking operation takes place, the brake pad is located radially outward in positive-locking connection with the brake carrier horns with, at the same time, the tolerance required for fitting and removing the brake pad in or out of the brake pad shaft being provided and a required thermal expansion compensation also being ensured. If a braking operation is now initiated, only a tilting of the brake pad in the region of the outlet-side carrier horn would be possible, which is, however, prevented by the friction force FR prevailing at the outlet-side brake carrier horn owing to the abutment of the brake pad side on the outlet-side brake carrier horn.
Owing to the abutment of the brake pad on the radially outer side of the positive-locking connection, when torque is introduced due to a braking operation, the rotation point of the brake pad is displaced from the outlet-side carrier horn toward the inlet-side carrier horn, whereby a rotation movement of the brake pad in a direction of a main rotation direction of the brake disc is effectively prevented.
According to advantageous developments, the pad retention spring is constructed as a leaf spring, a helical spring, a plate spring or as a rotary spring or torsion spring, which are all capable of retaining the brake pad in the brake-free state in positive-locking connection at the radially outer side of the carrier horns or of the brake pad.
According to an alternative embodiment, the pad retention system is constructed in such a manner that the pad retention spring is supported on a curved pad retention member which is secured to the brake caliper. The brake pad spring is constructed as a tension spring. With this arrangement, the brake pad can also be retained in positive-locking connection at the radially outer region of the carrier horns so that the desired action of rotation prevention in the event of braking is also effectively prevented with this arrangement.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.